The invention relates in general to heaters and in particular to a burner equipped with an ultrasonic atomizer and intended for smaller air heating appliances employed in non-stationary spaces, such as in vehicles, trailers, or tents, and having powers of less than 10 kW.
As is well known, ultrasonic atomizers for liquid fuel have a particularly satisfactory atomizing effect, only as compared to pressure atomizers. They require another design of the ignition and combustion systems of the burner, and a powerful flow of the supplied combustion air. However, in contradistinction to a vaporizing burner with or without a rotary distributor, short ignition and transition periods up to steady operating conditions can be obtained and aftersmoke upon turning off can be eliminated. In general, a better combustion can be ensured and thus the emission of noxious substances reduced. Also, spark plugs requiring substantially less power can be used instead of glow plugs.
A spatial separation of the ignition zone from the combustion zone and a separate supply of primary and secondary combustion air is known from German AS 12 57 396, for a conventional atomizing burner. In this prior art design, the separation of the two zones is effected by a housing shell in which the stream of the ignited mixture of atomized fuel and primary air is deflected, forced through a throttling slot and contacted with a countercurrently directed stream of secondary air. This arrangement requires an extraordinarily high amount of combustion air energy, and is unsuitable for ultrasonic atomizer burners.